Chris Wood's second-half brace ensured that Burnley condemned West Ham United to another Premier League defeat as Sean Dyche's men won 3-0 on a chaotic afternoon at the London Stadium.
Burnley were thankful to both substitute Wood and Ashley Barnes away from home, as a series of ugly fan protests from a particular section of the home supporters marred the Clarets' win over David Moyes and his struggling charges.
Aiming to bounce back from a poor showing against Swansea City last time out, the Hammers started with plenty of energy as Joao Mario slipped in Marko Arnautovic, who saw his driven effort kept out by Nick Pope after a retreating Ben Mee had pushed the frontman wide inside the box.
The hosts were clearly improved from the defeat in Wales and they again came close through Manuel Lanzini, who exchanged a neat one-two with Arnautovic, only to bend his effort high and wide from the edge of the box.
Burnley adopted a safety-first approach in the opening half with just one striker and Barnes often cut a rather isolated figure for the Clarets, whose best chance came when Jeff Hendrick found space on the turn, although James Collins was able to intercept the following pass before it reached Barnes.
West Ham continued to offer options in the final third, but once more they were let down by a lack of quality at the vital moment. Lanzini was able to break onto the end of a long ball forward to get the better of the Burnley defence, before opting for a cute finish that was saved by Pope's outstretched leg down low.
Dyche's charges might have grabbed a surprise lead in the second half when Barnes fired into the back of the net, only for the striker to be ruled offside as he broke off the back of the West Ham defence.
The away side soon introduced striker Wood and he made all the difference when he collected a long ball from Matthew Lowton to beat Angelo Ogbonna, before squaring for Barnes to finish first time with a wonderful effort on the edge of the area.
Scenes soon turned ugly at the London Stadium as a protesting fan entered the pitch. The invasion did the hosts no favours either, as Wood then bagged his side's second of the afternoon from Aaron Lennon's miscued shot once play had eventually resumed.
The second goal proved too much for a growing section of Hammers fans, who made their way down to protest in front of the directors' seats.
Thankfully the game resumed shortly after despite the continued protests in the stands, but things were to get even worse for the hosts as Joe Hart spilt a shot into the path of Wood, allowing the frontman to grab his second of the afternoon with a simple tap-in.
The goal spurred more protests in the stands as those sitting in the directors' area were advised to leave as police moved in to marshal the slowly-dispersing crowds down below.
The football continued on the field although fortunes failed to change for the beleaguered Hammers, who fell to a third loss by a three-goal margin in a row for the first time in almost 10 years.
WEST HAM UNITED (3-4-3): Hart; Collins, Ogbonna, Cresswell; Zabaleta, Kouyate, Noble, Antonio; Lanzini, Joao Mario (Hernandez 71'); Arnautovic
BURNLEY (4-5-1): Pope; Lowton, Tarkowski, Mee, Ward; Lennon, Cork, Westwood, Berg Gudmundsson, Hendrick (Wood 61'); Barnes (Vokes 89')
